A versatile and efficient approach for the synthesis of new biphenyl-based arsine ligands, by a Pd-catalyzed arsination to introduce the -AsPh(2) moiety, and then a Suzuki-Miyaura cross-coupling for biaryl construction is reported. By Pd-catalyzed arsination with n-Bu(3)SnAsPh(2) (1), (2-bromophenyl)diphenylarsine (2, 83%) was obtained. The Suzuki-Miyaura reaction between the bromoarsine 2 and aryl boronic acids bearing different substituents provided biarylarsine ligands (80-99%). The efficiency of catalysts derived from the new biarylarsine ligands was evaluated in the Pd-catalyzed arsination with perfluoroalkyl iodides (R(f)I). Outstanding activities of catalysts derived from Pd/methoxybiarylarsine ligands were found in this coupling reaction affording perfluoroalkyl arsines in very good yields (57-100%).

The oxidation of the free hydroxyl group of methyl 3,4:5,6-di-O-isopropylidene-D-gluconate 2 or its 2,3:5,6-di-O-isopropylidene analogue 3, the products of acetonation of D-glucono-1,5-lactone 1, has been attempted by alternative procedures. The oxidation of OH-2 in 2, or OH-4 in 3, with o-iodoxybenzoic acid (IBX) took place to afford the respective 2-keto 4 and 4-keto 7 derivatives in almost quantitative yields. In contrast, the oxidations with pyridinium dichromate were unsuccessful, and those using dimethylsulfoxide−acetic anhydride afforded low yields of 4 or 7. Selective removal of the isopropylidene groups in 4 or 7 with 88% aqueous acetic acid afforded, respectively, the methyl esters 5 or 8; whereas treatment with aqueous trifluoroacetic acid led to the free hexulosonic acids 6 or 9. The tautomeric preferences for the oxidation products 4 and 7, and their derivatives, have been established by 13 C NMR spectroscopy.

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